There are a number of cardiovascular diseases characterized by weakness of supportive connective tissue, i.e., syndrome of 'click murmur' (floppy) of the mitral valve, dissecting aortic aneurysm, cystic median degeneration of the aorta, Marfan's syndrome and aneurysms of the membranous septum. Currently, there is no satisfactory therapeutic program for these diseases. We now know that certain androgen-anabolic steroids in combination with B-adrenergic blockage can increase tensile properties of aortic tissue from an inbred strain of domesticated turkey. These animals may have genetic defects in connective tissue as suggested by development of spontaneous and lethal dissecting aneurysms. It is known from the reports of veterinary scientists that the incidence of dissection can be reduced by feeding androgens. The possibility that the drugs increase tensile properties of the abdominal aorta by altering collagen and elastin crosslinking was investigated using the technique of column chromatographic separation of (3H)NaBH4-reduced crosslinks. Androgen-anabolic steroid in the presence of Beta-adrenergic blockade quantitatively alters lysyl-derived borohydride-reducible crosslinks of collagen of turkey abdominal aorta. Testing of other steroids for an effect on tensile properties, collagen and elastin crosslinks and collagen types of turkey abdominal aorta and mitral valve will be carried out this year.